The present knowledge of the physical properties of the IGrM, both thermodynamical and chemical, is limited to
archival studies with known systems mainly at the high end of the mass and luminosity ranges. X-ray selection provides a more reliable way than optical selection of identifying virialized groups with a bona fide IGrM, but groups are typically at the limit sensitivity of the
ROSAT All Sky Survey (RASS) and their detection is biased towards peaked surface brightness objects [1]}, [2]}. Even though the advent of XMM-Newton and Chandra made available
deep surveys of limited areas providing less biased samples of groups, these systems are typically at moderate redshifts and they lack even global abundance measurements [3]}, [4]}. Optically
selected systems with a dedicated X-ray follow-up can circumvent some of the biases of the RASS X-ray selection
and provide some partial answer to the characteristic of the general population of groups [5]}.
